0001213900-26-045363
SEC filingRadiopharm Theranostics reported initial Phase 0/1 HEAT trial findings for 177Lu-RAD202 showing encouraging tumor uptake and favorable safety at 30 mCi, with DSMC approval to escalate to 130 mCi in the third cohort, advancing its HER2-targeted radiopharmaceutical program.
This 6-K filing discloses pivotal first-in-human clinical data from the Phase 0/1 HEAT trial (NCT06824155) for 177Lu-RAD202, Radiopharm’s proprietary HER2-targeted radiopharmaceutical. The results represent the earliest human evidence of target engagement and safety for this novel single-domain antibody (sdAb) platform, directly validating the company’s core therapeutic hypothesis. Meaningful tumor uptake — particularly in breast cancer lesions — at the minimal 30 mCi dose level confirms biological activity despite prior extensive therapies in all three enrolled patients, addressing a population with high unmet need. The absence of dose-limiting toxicities and exclusively low-grade adverse events strongly supports the compound’s tolerability profile, reducing near-term safety concerns that often derail radiopharmaceutical development. Critically, the favorable dosimetry — explicitly stated as 'within expected and clinically acceptable ranges' — provided the quantitative basis for the DSMC’s April 8, 2026 decision to approve escalation to 130 mCi, the next planned dose cohort. This advancement is not incremental: it transitions the program from biodistribution/pharmacokinetic assessment (Phase 0) into the therapeutic dose range where antitumor activity is anticipated. As noted by the Chief Medical Officer, signs of efficacy are expected at higher doses, making this escalation a prerequisite for demonstrating clinical benefit. For investors, this represents de-risking of the early clinical pathway and a tangible catalyst toward potential Phase 2 initiation, reinforcing the strategic value of Radiopharm’s differentiated sdAb platform in the competitive HER2-targeted oncology space.